Diesel fuel additive compositions for prolonged antistatic performance

ABSTRACT

An additive composition comprising at least one antistatic agent; and a strong acid, wherein the at least one antistatic agent and the strong acid are present in the additive composition in a ratio of from about 1:0.05 to about 1:1 is disclosed. There is also disclosed a fuel composition comprising a middle distillate fuel and the additive composition. Methods of making and using the compositions are also disclosed, Further, methods of improving and/or prolonging the conductivity of a fuel are disclosed.

DESCRIPTION OF THE DISCLOSURE

1. Field of the Disclosure

This disclosure relates to an additive composition comprising at leastone antistatic agent and at least one strong acid. The additivecomposition can be combined/blended/admixed with a middle distillatefuel to form a fuel composition. Methods of making and using theadditive and fuel compositions are also disclosed. Also disclosed aremethods of improving and/or prolonging the ability of an additivecomposition to impart effective conductivity to a fuel,

2. Background of the Disclosure

Certain middle distillate fuel compositions, particularly diesel fuels,are capable of generating static electricity, particularly when movingrapidly, such as when the fuel is being dispensed into a tanker or otherbulk container or vessel. While diesel fuels are not very volatile, thetankers used to transport diesel fuels are also used to transportgasoline, kerosene and other more volatile and flammable liquids. Evenafter the more volatile fuel is dispensed from the tanker, the vaporsmay still be present and pose a risk of fire or explosion from a sparkgenerated by the discharge of static electricity from the fuelcomposition.

These risks have become more acute in recent years with the increasedpopularity and use of low sulfur fuels and even more acute in recentmonths with the introduction of ultra-low sulfur diesel fuels. Theprocess used to remove the sulfur from the fuels also decreases theconcentration of other polar compounds in the fuel, which in turnreduces the ability of the fuel to dissipate a static charge.

To mitigate the risks of fire or explosion with low and ultra-low sulfurfuels, it has become common to add a conductivity improver to the fuelat or prior to the point of dispensing the fuel into a bulk container.The conductivity improver, as the name suggests, improves theconductivity of the fuel, thus permitting any static charge built upduring high volume transport of the fuel to safely dissipate withoutgenerating a spark. Conductivity improvers are also known as antistaticagents.

The most common type of conductivity improver or antistatic agent usedin fuels, particularly diesel fuels, has been the Stadis® brand ofantistatic agents sold by Innospec Fuel Specialties, LLC, Newark, Del.The Stadis® brand of antistatic agents contain sulfur. Sulfur-containingantistatic agents present a problem when used with additive concentratesthat contain basic nitrogen. Specifically, the ability to deliverconductivity improvement by a sulfur-containing antistatic agentdissipates very rapidly when used in additive concentrates containingbasic nitrogen because of a reaction between the two materials. This isdisadvantageous because it prevents pre-blending of these antistaticagents into additive concentrates that contain basic nitrogen. Manycomponents of a typical fuel additive concentrate may includenitrogen-containing compounds, such as dispersants, detergents, coldflow improvers, lubricity improvers, corrosion inhibitors, stabilizers,and the like. As a result, it is often necessary to add thesulfur-containing antistatic agents separately from the other componentsof the additive concentrate. Thus, these types of antistatic agents mustbe kept in a separate tank at the depot and added separately to thefuel. Accordingly, these types of antistatic agents, apart from theirinherent additional cost, require additional costs and complexity interms of storage, handling and dispensing.

Therefore, there is a need for compositions and methods to address thebuild-up and discharge of static electricity in middle distillate fuelcompositions. Moreover, there is a need for a multifunctional dieselfuel additive package that when stored does not lose the ability todeliver conductivity to the fuel.

SUMMARY OF THE DISCLOSURE

In accordance with the disclosure, there is disclosed an additivecomposition comprising at least one antistatic agent; and a strong acid,wherein the at least one antistatic agent and the strong acid arepresent in the additive composition in a weight ratio of from about1:0.05 to about 1:1.

Moreover, there is also disclosed a pre-blended additive compositioncomprising at least one antistatic agent; and a strong acid, wherein theat least one antistatic agent and the strong acid are present in theadditive composition in a weight ratio of from about 1:0.05 to about1:1.

In one embodiment is provided herein a method of improving theconductivity in a fuel comprising combining, with the fuel, a strongacid with a composition comprising an antistatic agent and a basic,nitrogen-containing component; wherein the strong acid is combined in anamount sufficient to neutralize at least a portion of the basic nitrogenin the component. In another embodiment, less than all of the basicnitrogen needs to be neutralized to stabilize deliverable conductivity.Thus, in some examples here only about 40%-70% of the basic nitrogenneeds to be neutralized by the use of additional strong acid. The amountof basic nitrogen to be neutralized can vary and may be impacted by bothsteric availability and basicity leading in one embodiment to less than40% of the basic nitrogen reacting with the antistatic agent.

Additional objects and advantages of the disclosure will be set forth inpart in the description which follows, and can be learned by practice ofthe disclosure. The objects and advantages of the disclosure will berealized and attained by means of the elements and combinationsparticularly pointed out in the appended claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the disclosure, as claimed.

DESCRIPTION OF THE EMBODIMENTS

The present disclosure relates to an additive composition comprising atleast one antistatic agent; and a strong acid, wherein the at least oneantistatic agent and the strong acid are present in a weight ratio offrom about 1:0.05 to about 1:1. The additive composition can becombined/mixed/blended with a middle distillate fuel to form a fuelcomposition. In order to improve and/or maintain the conductivity of thefuel, the strong acid can, in one embodiment, be combined/mixed/blendedwith the antistatic agent in an amount sufficient to neutralize at leasta portion (40-70%) or all of the basic nitrogen.

The phrase “improved conductivity” is used to indicate that the abilityof the additive package to provide conductivity to the fuel does notdecline by more than about 50% from an initial measure with theconductivity additive alone. This measure is taken within 3 hours ofstoring the additive composition at 90° C. For example, in oneembodiment the conductivity effect does not decline by more than about30% within that 3 hour period at 90° C. As a further example, theconductivity measure declines by no more than about 30% for a period ofat least 7 hours at 90° C. In some aspects, the conductivity measure canstill be at least about 50% of its initial measure after 10 hours 90° C.following the preparation of the additive composition. Thus anotherembodiment herein provides prolonged conductivity performance of theadditive package. In one embodiment, there is disclosed a method ofprolonging the conductivity performance of an additive compositioncomprising combining a strong acid with a composition comprising anantistatic agent, wherein the composition comprises a basic,nitrogen-containing component; and wherein the antistatic agent and thestrong acid are combined in a weight ratio of about 1:0.05 to 1:1.0Useful basic, nitrogen-containing components, such as dispersants, areknown to those skilled in the art, but can include for examplehydrocarbyl-substituted succinimides, polyetheramines, and Mannich basereaction products.

The term “conductivity benefit” is used to indicate that theconductivity imparted by the additive composition is sufficient toprovide a conductivity of the fuel of at least about 25 pS/m at the timeand temperature of delivery of the fuel. All examples herein are wellabove this value, when measured at room temperature.

The present compositions can be particularly suited for middledistillate fuel compositions. Middle distillate fuel compositionsinclude, but are not limited to, jet fuels, diesel fuels, and kerosene.In an aspect, the fuel is a low-sulfur fuel having less than about 500ppm sulfur, for example less than about 350 ppm of sulfur. In an aspect,the fuel can be an ultra-low sulfur diesel fuel or ultra-low sulfurkerosene. Ultra-low sulfur fuels can be generally considered to have nomore than about 30 ppm of sulfur, for example no more than about 15 ppmof sulfur, and as a further example no more than about 10 ppm of sulfur.The term “diesel fuel” is generally considered to be a generic termencompassing diesel, biodiesel, biodiesel-derived fuel, synthetic dieseland mixtures thereof. All disclosures herein to parts per million “ppm”are by mass unless otherwise indicated.

The present disclosure encompasses jet fuels, although these areconventionally not regarded as “low-sulfur” or “ultra-low sulfur” fuelsbecause their sulfur levels can be comparatively quite high.Nevertheless, jet fuels may also benefit from the conductivityimprovement of the present embodiments regardless of their sulfurcontent.

The antistatic agent for use in the disclosed compositions can in oneembodiment comprise, based on total weight, from about 5 to 25 percentof a polysulfone, from about 5 to 25 percent of a polymeric polyamine,from about 5 to 30 percent of oil-soluble sulfonic acid, and from about20 to 85 percent of solvent.

The polysulfone copolymers often designated as olefin-sulfur dioxidecopolymer, olefin polysulfones, or poly(olefin sulfone) can be orcomprise, for example, linear polymers wherein the structure isconsidered to be that of alternating copolymers of the olefins andsulfur dioxide, having a one-to-one molar ratio of the comonomers withthe olefins in head to tail arrangement. The polysulfones used hereinare readily prepared by the methods known in the art (cf. Encyclopediaof Polymer Science and Technology Vol. 9, Interscience Publishers, page460 et seq.).

The polyamine component of the antistatic agent disclosed herein can beor comprise, for example, a polymeric reaction product ofepichlorohydrin with an aliphatic primary monoamine or N-aliphatichydrocarbyl alkylene diamine. The polymeric reaction products can beprepared by heating an amine with epichlorohydrin in the molarproportions of from 1:1-1.5 in the temperature range of about 50° C. toabout 100° C. Generally, with aliphatic monoamines the molar ratio canbe about 1:1. The initial reaction product is believed to be an additionproduct. The aminochlorohydrin upon reaction with an inorganic base canthen form an aminoepoxide. The aminoepoxide, which can contain areactive epoxide group and a reactive amino-hydrogen, can undergopolymerization to provide a polymeric material containing several aminogroups. The ratio of epichlorohydrin to amine and the reactiontemperature used are such that the polymeric reaction product cancontain from 2 to 20 recurring units derived from the aminoepoxide.

Generally, the amount of strong acid incorporated in the additivecomposition can be an equivalent amount, that is, a sufficient amount ofstrong acid to, in one embodiment, neutralize at least a portion of orall the basic nitrogen, such as a dispersant, although lesser or greaterthan the equivalent amount can be used. In another embodiment, an amountof the strong acid sufficient to neutralize a portion of the basicnitrogen can be used effectively to achieve the improved antistaticperformance of the additive package. Thus, the antistatic agent and thestrong acid can, in one embodiment, be present in a weight ratio ofabout 1:0.05 to about 1:1 depending upon the amount of basic nitrogenpresent in the additive composition.

The compositions and methods of the present embodiments can provideconductivity to a fuel of at least 25 pS/m at the time and temperatureof delivery. This conductivity is sufficient to meet the proposed newASTM standard for conductivity in diesel fuels (ASTM D975 and amendmentsand appendices thereto) measured according to any appropriate testprocedure, including but not limited to ASTM D2622 and ASTM D4951. Thislevel of conductivity can be obtained and sustained for extended periodsof time by the present embodiments. The disclosed fuel composition canexhibit improved conductivity as compared to a fuel composition devoidof the additive composition. Moreover, the disclosed fuel compositioncan exhibit prolonged conductivity as compared to a fuel compositiondevoid of the additive composition.

The fuel compositions of the present disclosure can contain supplementaladditives in addition to the antistatic agent described above. Thesupplemental additives include, but are not limited to,dispersants/detergents, antioxidants, carrier fluids, metaldeactivators, dyes, markers, corrosion inhibitors, biocides, additionalantistatic agents, drag reducing agents, demulsifiers, dehazers,anti-icing additives, antiknock additives, cold flow improver,anti-valve-seat recession additives, lubricity additives and combustionimprovers.

The additives used in formulating the fuels of the present disclosurecan be blended into the base fuel individually or in varioussub-combinations. However, it is recommended to blend all of thecomponents concurrently using an additive concentrate as this takesadvantage of the mutual compatibility afforded by the combination ofingredients when in the form of an additive concentrate. Also use of aconcentrate reduces blending time and lessens the possibility ofblending errors. In an aspect, at least two components, such as theantistatic agent and the strong acid, can be pre-blended.

Thus there is also provided herein a method of prolonging theconductivity effect of an additive package in a fuel comprising:combining, with the fuel, an additive package comprising a strong acidand an antistatic agent, wherein the additive package comprises a basic,nitrogen-containing component; and wherein the antistatic agent and thestrong acid are combined in a weight ratio of from about 1:0.05 to about1:1.

Examples 1-4 were prepared as blends of HiTEC® 4130WM, Stadis® 425 andWitconic™ 1298 Hard Acid. HiTEC® 4130WM is a multifunctional diesel fueladditive that contains a polyisobutylene succinimide, a cold flowimprover, an ester lubricity additive, a demulsifier, a corrosioninhibitor and solvents and is available from Afton Chemical Corporation.HiTEC® 4130WM typically contains 0.032% nitrogen. Stadis® 425 is asulfur-containing antistatic additive and is available from InnospecFuel Specialties, LLC. Witconic™ 1298 Hard Acid is predominantlydodecylbenzene sulfonic acid (DBSA) and is available from Akzo NobelSurface Chemistry, LLC. The sample formulations were sealed in glassvials and placed in an oven set to 90° C. for 16 hours. No fuel waspresent for the aging. This accelerated aging period is thought to beequivalent to about three (3) months storage at 20° C. After allowingthe samples to cool at the end of the aging period, each was evaluatedfor its effect on improving the conductivity of an ultra-low sulfurdiesel (ULSD) fuel (obtained from the Citgo pipeline terminal inRichmond, Va.) at 22° C. The results are shown in Table 1. The test ULSDfuel had a measured conductivity of 0 picosiemens per meter (pS/m)without antistatic additive and 504 pS/m when treated with 5 ppm ofStadis® 425 by itself. All 4 example blends were added to the fuel suchthat the treat rate of Stadis® 425 was 5 ppm.

TABLE 1 Measured fuel Mass % in Blend conductivity @ % loss inWitconic ™ Blend 22° C. after blend conductivity HiTEC ® Stadis ® 1298Hard Treat Rate aged 16 hr @ performance Example # 4130WM 425 Acid (ppm)90° C. (pS/m) of blend 1 99.42 0.29 0.29 1720 506 0.0 2 99.49 0.29 0.221720 314 37.7 3 99.54 0.29 0.17 1720 143 71.6 4 99.71 0.29 0.00 1720 5589.1

A base multifunctional diesel fuel additive (“MFDA”) composition isshown in Table 2. The ester lubricity additive is an ethylene glycoldiester of dimer acid. The cold flow improver is HiTEC® 4566 fueladditive (available from Afton Chemical Corporation), containingethylene vinyl acetate copolymer and a nitrogen-containing waxanti-settling component to improve the low temperature filterability ofthe finished fuel. The cold flow improver contains 0.026% nitrogen. Theconductivity improver (antistatic agent) is Stadis® 425 and the solventis Aromatic 100 fluid supplied by ExxonMobil Chemical.

TABLE 2 Base MFDA formulation Function Weight % Ester lubricity additive22.00 Cold flow improver 25.33 Conductivity improver 1.33 Aromaticsolvent 51.33

This base formulation was then mixed with varying amounts of Witconic™1298 (DBSA) and the resulting blends (Examples 5-8) were added to anULSD fuel (obtained from ExxonMobil Corporation) at 450 ppm. For each ofthe Examples 5-8, the initial conductivity imparted to the fuel wasmeasured immediately after blending the components (Column A).Additional blends were also stored at 90° C. for 16 hours as describedabove. After aging, these blends were added to the ExxonMobil ULSD fueland the fuel's conductivity was again measured (Column B). The resultsare shown in Table 3.

TABLE 3 Column B Column A Measured fuel Mass % in Blend Initial measuredconductivity @ 22° C. % loss in Base Witconic ™ 1298 fuel conductivityafter blend aged 16 hr conductivity Example # MFDA Hard Acid (pS/m) @90° C. (pS/m) performance 5 99.89 0.11 778 769 1.2% 6 99.91 0.09 760 60021.1% 7 99.98 0.02 750 240 68.0% 8 100.0 0.00 745 135 81.9%

The results in Table 3 indicate that lesser amounts of the strong acid(Witconic™ 1298 Hard Acid) were needed to achieve the prolonged impartedconductivity because of the reduced amounts of a basic,nitrogen-containing component in the base multifunctional diesel fueladditive composition. Comparative Example 8, having no exogenous strongacid, presented a radical loss in conductivity (81.9%) whereas theInventive Examples 5-7 illustrate the ability of the aged additivepackages provided herein to deliver effective conductivity to fuelscontaining an antistatic agent.

For the purposes of this specification and appended claims, unlessotherwise indicated, all numbers expressing quantities, percentages orproportions, and other numerical values used in the specification andclaims, are to be understood as being modified in all instances by theterm “about.” Accordingly, unless indicated to the contrary, thenumerical parameters set forth in the following specification andattached claims are approximations that can vary depending upon thedesired properties sought to be obtained by the present disclosure. Atthe very least, and not as an attempt to limit the application of thedoctrine of equivalents to the scope of the claims, each numericalparameter should at least be construed in light of the number ofreported significant digits and by applying ordinary roundingtechniques.

It is noted that, as used in this specification and the appended claims,the singular forms “a,” “an,” and “the,” include plural referents unlessexpressly and unequivocally limited to one referent. Thus, for example,reference to “an antioxidant” includes two or more differentantioxidants. As used herein, the term “include” and its grammaticalvariants are intended to be non-limiting, such that recitation of itemsin a list is not to the exclusion of other like items that can besubstituted or added to the listed items.

While particular embodiments have been described, alternatives,modifications, variations, improvements, and substantial equivalentsthat are or can be presently unforeseen can arise to applicants orothers skilled in the art. Accordingly, the appended claims as filed andas they can be amended are intended to embrace all such alternatives,modifications variations, improvements, and substantial equivalents.

1. An additive composition comprising: at least one antistatic agent;and a strong acid, wherein the at least one antistatic agent and thestrong acid are present in the additive composition in a weight ratio offrom about 1:0.05 to about 1:1.
 2. The additive composition of claim 1,wherein the antistatic agent comprises a mixture comprising apolysulfone, a polymeric polyamine, a sulfonic acid, and a solvent. 3.The additive composition of claim 1, wherein the antistatic agentcomprises, based on total weight, about 5 to about 25% of polysulfone,about 5 to about 25% polymeric polyamine, and about 5 to about 30%oil-soluble sulfonic acid.
 4. The additive composition of claim 3,wherein the oil-soluble sulfonic acid is or comprises an acid selectedfrom the group consisting of benzenesulfonic acids and alkylnaphthylsulfonic acids.
 5. The additive composition of claim 1, wherein thestrong acid is or comprises an oil-soluble acid.
 6. The additivecomposition of claim 1, wherein the strong acid is dodecylbenzenesulfonic acid.
 7. The additive composition of claim 1, furthercomprising a basic, nitrogen-containing component.
 8. The additivecomposition of claim 7, wherein at least two components of the additivecomposition are pre-blended.
 9. A pre-blended additive compositioncomprising: at least one antistatic agent; and a strong acid, whereinthe at least one antistatic agent and the strong acid are present in theadditive composition in a ratio of from about 1:0.05 to about 1:1.
 10. Afuel composition comprising: the additive composition of claim 1; and amiddle distillate fuel.
 11. The fuel composition of claim 10, whereinthe middle distillate fuel is an ultra-low sulfur diesel fuel.
 12. Thefuel composition of claim 10, wherein the fuel composition exhibitsimproved conductivity as compared to a fuel composition devoid of theadditive composition.
 13. The fuel composition of claim 10, wherein thefuel composition exhibits prolonged conductivity as compared to a fuelcomposition devoid of the additive composition.
 14. A method ofimproving the conductivity in a fuel comprising: combining, with thefuel, a strong acid with a composition comprising an antistatic agentand a basic, nitrogen-containing component; wherein the strong acid iscombined in an amount sufficient to neutralize at least a portion of thebasic nitrogen in the component.
 15. The method of claim 14, wherein theantistatic agent is or comprises a mixture comprising a polysulfone, apolymeric polyamine, a sulfonic acid, and a solvent.
 16. The method ofclaim 14, wherein the basic, nitrogen-containing component is ahydrocarbyl-substituted succinimide derived from ahydrocarbyl-substituted succinic anhydride and a polyamine.
 17. Themethod of claim 14, wherein the strong acid is dodecylbenzene sulfonicacid.
 18. The method of claim 14, wherein the antistatic agent and thestrong acid are combined in a weight ratio of from about 1:0.05 to about1:1.
 19. A method of improving the conductivity in a fuel comprising:combining, with the fuel, a strong acid with a composition comprising anantistatic agent, wherein there the composition comprises a basic,nitrogen-containing component; wherein the antistatic agent and thestrong acid are combined in a weight ratio of from about 1:0.05 to 1:1.20. A method of prolonging the conductivity effect of an additivepackage in a fuel comprising: combining, with the fuel, an additivepackage comprising a strong acid and an antistatic agent, wherein theadditive package comprises a basic, nitrogen-containing component; andwherein the antistatic agent and the strong acid are combined in aweight ratio of from about 1:0.05 to about 1:1.